Automatic telephone system



Oct 9, 1928.,

A. J. RAY

" AUTOMATIC TELEPHONE SYSTEM Orizinal Filed Feb. 8, 192a Patented Oct. 9, 1928. r I I I UNITED STATES PATENT, orrlce.

ARTHUR J. RAY, or .CIUBAI, ILLINOIS, Assrenon, BY Ma ts ASSIGNMENTS, 'ro Auro- MATIC 1311121 01RIC INC., OF CHICAGO, ILLINOlS, A CORPORATION OFDELAWABE.

AUTOMATIC TELEPHONE svs'rn vr.

Application filed February 8 1926, Serial No. 86 ,754 Renewed September 29, 1927.

This invention relates to automatic tele- It at once becomes apparent that in asysphone systems in general, but more espetern supplying dial tone through the line cially to automatic party line systems in relays of the first selectors, subscribers on a which a switch, commonly known as a re partyline holding conversation, one having 5 verting call switch, is connected-to a callsignalled the other in the manner described ing line responsiveto the dialing of a certain above, will hear the dial tone during their number when the c lling subscriber and the entire conversation if no preventative means 60 called subscriber are on'the sameline. are provided. I

A system of this kind is shown and de- It is the object of this invention to pro;

1 scribed in the U. S. Patent No.-1,520,268 to vide means for preventing the dial tone John Wicks. In such a system when. 'a from being heard by party line subscribers subscriber on a party line wishes to signal during conversation, in systems of this kind. 65 another party on the same line, he removes This is accomplished in this invention by his receiver, dials a special number which especially equipping those second selectors causes a reverting call switch to be connect which have c ss o he reverting call ed to the line via an individual lineswitch switches so that when: ground potential is and one or more selector switches. After removed from the holding conductor at a 7 dialing the nu1nber,the calling subscriber reverting call switch in use, the first selecr'eplaces his receiver. The reverting call tor and the line switches associated withthe Z0 switch then functions to ring the bells of connection are not released, but the second both the calling and the called subscriber unselector in use disengages its wipers from til the called subscriber'removes his receiver the-bank contacts, and permits the reyert- 7 to answer the call, or until the calling sub,- ing callswitch to restore to normal. The scriber momentarily removes his receiver, current supply for the transmitters of the should the called, subscriber tail to answer. talking parties is then furnished through Vhcn the called party answers, ground po the line relay of this second selector.

tential is removed from. the holding con- The operation ofa system employing the 80 ductor which causes the restoration of the above generally described method of prereverting call switch and the other switches, venting two party line subscribers from the lineswitch and the one .or more selectors, hearing the dial tone during conversation associated therewith; The bridge across the is'described fully in the, following descripline at the calling and called substations tion, in so far as this invention is concerned, 5

causes a reoperation of the lineswitch, this referencesbeing had to the accompanying switch'again seizing a selector switch. The drawing, which isa circuit diagram of a current supply for the two transmitters of partof an automatic telephone system cmthe talking parties is furnished through the bodying, the invention; 7 line relay'of the last seized selector. In the drawing, reference character E 0 In the larger telephone exchange systems. represents a first selector, E represents a especially those employing primary and secsecond selector and the rectangle labeled R 40 ondary line switches and first and second indicates a reverting call switch which may selectors, provision maybe made to give a be of the type shown and described in the calling subscriber a signal to indicate when above mentioned reference. The first selec- 95 he may commence dialling. This is done, in tors are, accessible "from primary line order to eliminate the danger of the calling switches, or secondary line switches as the A5 subscriber commencing to dial before the .case may be, and are equipped to furnish.

line switches have been given sufficient time dial tone from the'dial-tone machine T. In 7 to operate and prepare a first selector for the banks ot'thefirst selectors, access is had 0 operation... The commonway, to give this to the; variousjgroups of secondflselectors. signal is to superimpose tone current on In one level of these banks access is bad to 1* the grounded conductor to which the" line special second selectors. The specialsecond relays of the first selectors are connected. selectors as well as the regular second selec- The calling subscriber hears this tone as tors, in-turn,. may have access to third se- 5' soon as a first selector has been seized. lectors, or connectors, depending on the size lease relay 111 at armature 121.

- ondselectors, or the first selectors.

To describe the operation of the system illustrated and particularly the operation of the special selector, the manner in which one subscriber is signalled when another subscriber on the same party line wishes to talk to him will be considered. To initiate the call, the calling subscriber removes his receiver and dials the proper number. Removing the receiver causes the lineswitch individual to that party line to operate and select a trunk to an idle first selector. It

' secondary lineswitches are used, the primary lineswitch selects a trunk to an idle second-- ary lineswitch, which in turn operates to select a trunk to an idle first selector. It may he assumed that selector E is the one selected. A circuit is immediately closed for the line relay extending from the bridge across the line at the calling substation over the talking loop to bank contacts 16 and 17, resting'contacts and armatures 18 and 19, through the upper and lower windings of line relay 25, to battery and through the Winding of the tone machine T to ground, respectively. The dial tone is heard by the calling subscriber indicating that he may commence dialing. Relay 25 operates and prepares the selector E to receive-the first digit.

The operation of a selector identical to the selector E is described in detail in the above mentioned U. S. Patent No. 1,520,268. The selector E oaerates in response to the first digit dialed y the calling subscriber to raise itswipers opposite the proper level of bank contacts in which access is had to the special second selectors, automatically rotates its wipers to select a trunk to an idle special second selector, and then extends the connection thereto. It may be assumed that the trunk selected is the one terminating in the bank contacts 105107, inclusive, extending to special second selector E. A circuit is immediately established for the line relay 110 whichextends over the subscribers line loop through the operated lineswitches to bank contacts 16 and 17, armatures 18 and 19 and their working contacts, wipers and 37, bank contacts 105 and 107, conduc-,

tors 108 and 109, armatures 130 and 133 and their resting contacts, through the upper and lower windings of the line relay 110 to battery and'ground, respectively. Line relay 110 operates and closes a circuit for re-,

Release relay 111 operates and at armature 122 places ground on the holding conductor 28 thereby armature 124-falls back.

.groundingthe bank contact 106 and the multiples thereof to mark this selector E tical magnet 117 which may betraced from ground at the resting contact and armature 132, armature 121 and the resting contact, armature 123 and the working contact, through the winding of the series relay 112, through the winding of the vertical magnet 117 to battery. Vertical magnet 117 operates accordingly and steps the wipers 145- 147, inclusive, opposite the level of bank contacts in which access-is had to the re- I verting'call switches. cam arrangement closes the shaft springs 137, these springs being closed only when the shaft'is raised to this particular level in which access is had to the reverting call switches. Series relay 112 is energized in series with the vertical magnet 117, and being slow acting is maintained operatedduring the entire vertical movement. In operating, series relay 112 prepares an initial energizing circuit for the stepping relay 113 at "armature 124.

Ofi normal springs 136 are closed upon the first vertical step of the switch wipers there'- by completing the circuit for the stepping relay 113 which may be traced from ground by way of armature 122 and. the working contact, normally closed springs controlled by armature 128, working contact and armature 124, closed olt-normal springs 136, through the winding of the stepping relay 113 to battery. Stepping relay 113 energizes: and prepares a circuit for the rotary magnet 118 at armature 125, and closes a temporary locking circuit for itself at armature'126 from ground at the resting contact and armature 132, working contact and armature 126, normally closed interrupter contacts 135, off-normal springs 136, through the winding of relay 113 to battery. I

At the end of the vertical movement series relay 112 deenergizes and closes a circuit for the rotary magnet 118 which may be traced from ground at armature 122 and the working contact, normally closed springs controlled by armature 128, normally closed springs controlled by armature 1241, working contact and armature12'5, through the winding of the rotary magnet 118 to ba .tery.

Relay 113 is maintained energized over the temporary locking circuit after Rotary. magnet 118 operates and rotates the switchWi-pers 1451-17 into engagement with the first set of bank contacts in the selected level and near I ground potential will the end of its stroke separates the inter rupter springs 135. 7 The separation of springs 135 opens the temporary locking circuit or the stepping relay 113. 'Relay 113 then deenergizes and opens the circuit of the rotary magnet 118 at armature 125, and also opens another point in the temporary locking circuit at armature 126. Rotary magnet 113 deenergizesand in releasing its armature again closes the interrupter springs 135.

If the reverting call switch accessible in the first set of bank contacts is busy at this time, ground potential will be present on the again energizes and rotates the switch wiper 145-147-mto 'engagement'with the next set 01 bank contacts. This alternate operation of the stepping relay 113 and the rotary magnet 118 continues until the switch wipers are rotated into engagement with the bank contacts terminating a trunk to an idle reverting call switch.

It may be assumed that the reverting call switch connected to the trunk terminating in the bank contacts 3840, inclusive, is the first idle switch accessible at this time. No be present on the test contact 39, therefore no circuit will be closed for the stepping relay 113 when the switch wiper 146 engages thetest contact 39. Since no circuit will again be closedior the rotary magnet 118, the switch wipers 145147'will be arrested in engagement tacts 38-40, respectively. During the rotary movement of the switch wipers of selector E, ground potential was present on both.

ends of the winding of relay'115, ground being supplied to the upper'terminal from the grounded conductor 28 by way of-the normally closed springs controlled by'a-rmature 128and the normally closed springs 138, and to thelower terminal fromthe grounded busy test contacts by way of the private wiper 146, armature 131 and the resting contact, resting contact and armature 127. Since ground potential is now absent from theby the wiper 146,

test contact 39 engaged switching relay115 energizes over circuit from ground on "the upper terminal of the winding of switching relay 115, through the winding 135, 05 winding normal springs 13o, through the of the stepping relay 113 to eating contacts, wipers with the bank con- 114 operates as soon as relay armature 122, and.connects ground potential of th s relay, interrupter springs tery. The resistance of the winding of relay 115 is high enough to prevent sufiicient current flow to cause the operation of the stepping relay 113 at this time. Switching relay 115 operates, however, and extends the connection to the reverting call switch .by way of armatures 130 and 133 and the worlr- 145 and 147, bank contacts 38 and40, and conductors 54 and 56 connected to the reverting call switch- Relay 115 also connects the test wiper 146 to the holding conductor 28" at armature. 131; and maintains the circuit of the release magnet 116open by disengaging armature 132 from its resting contact. the 'operationof armatures 130 and 133, liner'elay 110 is disconnected at the resting contacts of these armatures. Relay 110 deenergizes and releases its armature. The circuit of the re lease relay 111 is opened, but the relay being slow acting, maintains its trac'ted for a short interval thereafter. 7

By the extension of the loop connection .over conductors 54-56 to the reverting call theserelays'in the reverting call switch prepares this switch-t0 receive the next digit dialled and also places ground potential on the holding conductor to maintain the selector E, the selector E, and the preced'ng line switches operated in the wellrnown manner, this taking. place before the release relay 111 has had time to release its armatures and remove ground from conductor 28" and armature 122. Ordinarily the holding conductor remains extended straight through all the oper sited-selectors and lineswitches, all these; switches being held operated from ground supplied to this conductor from the last operated switch. In this new selector E on this particular level (springs 137 having been closed by the movement of the switch shaft to thislevel), the special release relay 111 restores its to the holding conductor'28 at armature 128 independent of the ground supplied from the revertlng call switch over 'the holding conductor 55; prepares aspecial release cireuitfor the release magnet 116, which is independent of the armatures of'relays '110 and 111, at armature 129; andopens a point in the test circuit at armature 127. Switching relay 115 isv now maintained operated from ground on the holding conductor 55,.

bank contact 39,wiper'146, armature 131,

springs 138, through the winding of relay, 115, interrupter contact" 135,.0fi normal springs136, through the winding of the armatures atv and the 'working contact, normally closed in the drawing, but particular reference is scriber.

111 at armature 121.

made to the one shown in the above referred to U. S. Patent, No. 1,520,268, its operation being described therein. j

In response to the dialing of the next digit, the reverting'call switch is operated and places its wipers on the proper set of contacts preparatory to signaling the called sub- After completing the dialing of thenumber, the calling subscriber replaces his receiver. Removing the bridge across the line causes the reverting call switch to send out the proper signaling current on the party line to alternately signal the calling and called subscribers. The signaling continues until the called subscriber removes his receiver'in answer to the ringing of his bell. In response to the replacing of the bridge across the conductors of the line now connected to the reverting call switch, the reverting call switch functions to disconnect the signaling current, disconnects ground potential from the holding conductor 55, releases and restores to normal.

The removal of ground from the holding conductor 55 opens the circuit of the switching relay 115, permitting relay 115 to de energize. Line relay 110 is again connected across the conductors 108 and 109 at armatures 130 and 133 and the resting contacts; test wiper 146 is disconnected from the holding conductor at armature 131; and a circuit is closed for the release magnet 116 at armature 132; Release magnet 116 operates to restore the switch wipers 141F147, inclusive, tonormal. Since relay 110 now bridged across the conductors 108 and 109, it again closes the circuit of the release relay Relay 111 operates and opens the circuit for the special release relay 11s at armature 122 and the resting contact and again places ground on the holding conductor 28 and the working contact of this armature. The special release relay 11 i is made slow acting to maintain the circuit of the release magnet 116 closed at armature 129 a sutlicient length of time to permit the complete operation of the release magnet. With the restoration of the switch wipers to normal, the shaft springs 137 and also the springs 13 1 and 136 are separatcd'as is their normal condition. The selector E is now in its normal condition with the exception that line relay 110 and release relay 111 are operated, talking current for the transmitters of the calling and the called subscribers being supplied through the windings oi? theline relay 110, and the selector E and the preceding line switches being held operatedin the usual manner by ground on conductor 28 supplied thereto at armature 122 and the working contact. The two subscribers may now hold conversation.

At the termination of the conversation.

tor E and the preceding lineswitches in the usual manner. I g

It is self evident that the selector E" Wlll function as anordinary second selector when operated to any level except the level at which the shaft springs 137 are closed.

ll hen the selector E is operated to any other level, the special release relay lll remains inoperative. With this relay ina deenergised position, the circuits in the selector E are the same as, and function eXactlyas, do

the circuits of the selector E'and the operation is identical. it is thereforethoughtunnecessary to describe the operat on of the .cc'tor 1 1 when operated to any other level.

The invention, its features and operation lnivf been described, what isthought to be-new and is desired to have protected by Letters Patent is specifically stated in the appended claims.

What is claimed is: r

1. In a telephone system, a first automatic switch, a second automatic switch, a third switch, means for extending a connection through the first and-secondswitches to said third switch, means in said third switch operative responsive to the establishment of said connection formaintaining said three switches operated, means for releasing said hird switch, means for releasing said second L switch responsive to the release of said third 1 switch, and means in said second switch for maintaining said, first switch operated independent of said third switch. 2. In an automatic switch, a switchin relay, a linerelay a release relay, a release magnet, a circuit for said release magnet including contacts on all said relays, and. a second circuit for said release magnet effective responsive to an operation of said switching relay independent of said line relay and said release relay. v

3. In an automatic switch, a switching relay, a line relay, a release relay, a release magnet, a circuit for said release magnet ineluding contacts on all said relays, and a second circuit over which said'release magnet is operates responsive to an operation of said switching relay independent or said line relay and said release relay, said second'eircuit being effective when said switch is operated to a certain level andinefiective when operated to another level.

4:. In a party line telephone system, a

selector and a secondselector for extending a calling line to said reverting call switch in order to signal acalled station on the same line, means for releasing the second selector when the called party responds, and means for preventing the release of the ii rstselectorwhen the called party responds.

In a party line telephone system, a reverting call switch, means including a first selector and a second selector for extending a calling line to said reverting call switch in order to signal a called station on the same line, means in the reverting callswitch for ,tertermg with the conversation.

causing the release of the second selector when the called party responds, and means in the second selector for preventing the release of the first selector when the called party responds.

6. In a party line .telephone system, a reverting call switch, means including a line switch, a first selector, and a second selector for extending a calling line to said'revert-ing call switch in order to signal a called station on the same line, and means for supplying talking current to the calling l ne through windings of the selector.

7 In a selector switch arranged-to normally provide a through holding circuit between preceding and succeeding switches, a

line relay. of said second local circuitilfor holding the preceding switch while the selector is being operated, and" means for locally closing another holding circuit to the preceding switch in case the v selector is operated to a particular position.

8. In a selector having access to groups of trunk lines and arranged to normally provide a through holding; circuit extending back from a selected trunk to a preceding switch, means for locally closingthe holding circuit to the preceding switch after the selector is operated in case the selector has selected a trunk in a particular group.

9. In a party line telephone system, a

reverting call switch, means including a' first numerical switch and asecond numerical switch for extending a calling line to said reverting call switch in order to signal a called station on the same line, and means for supplying talking current to the calling line through windings of the line relay of said second numerical-switch 10. In a party line telephone; system, a

line, a reverting call switch, -a first selector,

a second selector, connecting means-for connecting said line to said first selector, means including said connecting means, said first selector, and said second selector for extending a connection from said line to said reverting call switch in order to signal a called station on the same line, and means for supplying tallring curent to the calling line through windings of the line relay of said second selector. 1

first and a second selector and controlled'by a calling party on said line for extending a connection from said line to said reverting call switch in order to signal a called party on said line, dial tone mechanism associated with the first selector only, means responsive to the answeringof'the call by the called party for'releasing said reverting call switch andsaid second selector, and means for pre-' venting the release of said lirstselec'tor in order to'prevent said dial tone mechanism from placing a dialtone on the line and in- 12 In a telephone system in which a'called party on a party line is signalled by a reverting call switch which is connected to the line by way of a first selectorand one or iore succeeding switches when a calling party on the same line wishesto converse with the called party, and in which the first selectors are provided with dial tone mechanism, the method of preventing the dial tone from-interfering with the conversation which consists in preventing the release of the first selector after the called party responds while.

the succeeding switches of the reverting call switch are released.

13. In a telephonesystem in which connections are extended by successively operating a series of automatic switches, means for ma ntaining all the operated switches in position under the control of the last switch,

and means in an intermediate switch operaating a series of automatic switches and in which all switches are normally released responsive to the release of the last switch,

means in an intermediate switch efiective in case it is operated to a particular position for preventing the release of the preceding switches when the last switch is released. I

15. In a telephone system in which con nections-are extended by successively oper 'ating a series of automatic selecting switches and in which all the switches are normally released responsive to the release of the last switch, means in an intermediate switch 'ettective in case a succeedingswitch is of a particular kind for preventing the release of the preceding switches when the last switch is released.

16. A telephone system in whichv connections are extended by successively operating aseries of automatic switches and in which eachswitch is arranged to hold the preceding switches operated over a local. circuit while it is being operated and to extend the holding circuit to a succeeding switch after it has been operated, characterized in that means are provided in one switch which becomes eilective under certain conditions for closing another local circuit for holding the preceding switches independent of the succeeding switches.

17; In a telephone system in which connections are extended by successively operating a series of automatic switches,'means for holding all the operated switches in position over a through holding. circuit under the control of the last switch operated, and

18. In a telephone system in whichconnections are extended by successively operating a series oi automatic switches and in which each switchhas a release relay which is actuated when the switch is seized by a precedin switch operated and is deactuated when the switch is operated to seize a succeeding switch separate means in one switch operable under certain conditions and controlled by the release relay otthe switch in its deactuated position for maintaining the preceding switch operated. p

In witness whereof I hereunto subscribe my name this fourteenth day of January, A. v

ARTH R 'J. RAY.

or switch to maintain the preceding 

